Center tap potentiometer center biased by linearly movable microswitch actuating control rods



Nov. 10, 1970 K E. NEUMEIER CENTER TAP POTENTIbMETER CENTER BIASED BY LINEARLY MOVABLE MICROSWITGH ACTUA'IING CONTROL RODS 2 Sheets-Sheet 1 Filed May 1, 1968 I l J54 INVENTOR.

X111. 1:. JIA'IIMEIER BY Nov. 10, 1979 K. E. NEUMEIER 3,539,748

CENTER TAP POTENTIOMETER CENTER BIASED BY LINEARLY MOVABLE MICROSWITCH ACTUATING CONTROL RODS Filed May 1, 1968 2 Sheets-Sheet 2 ill m in Z" IN V EN TOR. MIL E. .A/[VML'IEE United States Patent 3,539,748 CENTER TAP POTENTIOMETER CENTER BIASED BY LINEARLY MOVABLE MICROSWITCH ACTU- ATING CONTROL RODS Karl E. Neumeier, Stillwater, Minn., assignor to Programmed 8: Remote Systems Corporation, St. Paul, Minn, a corporation of Minnesota Filed May 1, 1968, Ser. No. 725,617 Int. Cl. H0111 21/24 U.S. Cl. 200-153 14 Claims ABSTRACT OF THE DISCLOSURE A control switch of the rotary type having a center ofi? position and controlling movement of a load in two different directions by moving the switch to either side of a center off position. The switch controls a center tap potentiometer and not only turns the load on and off and controls the direction of movement of a load, but also controls speed of the load. The farther the switch is moved from its off position the faster the load is moved. The switch utilizes an improved arrangement for positively returning the switch to its center off position whenever it is released so that very accurate control of the load can be obtained.

BACKGROUND OF THE INVENTION Field of the invention The present invention pertains to rotary control switches having a center off position and movable in two opposite rotational directions.

Background of the invention One of the basic problems in previous rotary switches has been the lack of precise centering of the switch to its 011 position when the switch is released. Torsion springs weaken, become loose at their center position, and generally are unsatisfactory. Linear switches are satisfactory, but some operators prefer a rotary switch for controlling rotary motion.

SUMMARY OF THE INVENTION The present invention relates to a rotary control switch which utilizes a positive centering device by using a gear drive to control a rotary control element. The switch uses linearly actuating springs for centering the switch. A gear is drivably mounted directly onto the switch control handle shaft and this gear in turn engages another gear and drives a rotary control element such as a rotary potentiometer. A pair of spring loaded rods are retained in a part annular slot defined in the first gear. The rods are spring loaded so that the springs act on the rods to exert a force tending to rotate the gear to a stopped position when there is no external force on the actuating handle.

The unit can be used With on and off limit switches to obtain two way action where there is only single polarity direct current available, or can be used to direct the power units without the on-off switches when proper power is available.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a fragmentary top plan view of a control panel mounting a control switch made according to the present invention;

FIG. 2 is a side elevational view of the device of FIG. 1, with parts in section and parts broken away;

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FIG. 3 is a sectional view taken as on line 3-3 in FIG. 2;

FIG. 4 is an enlarged sectional view taken as on line 4-4 in FIG. 2;

FIG. 5 is a schematic representation of a typical control circuit used with the switch construction of FIGS. 1-4;

FIG. 6 is a fragmentary enlarged side elevational view' showing a modified form of the invention employing micro switches and;

FIG. 7 is a modified control circuit used with the present invention and employed when the switch as shown in FIG. 6 is used.

DESCRIPTION OF THE PREFERRED EMBODIMENT The control switch shown generally in 10 is installed on top panel 11 of a control console. The top panel is shown only fragmentarily. The switch includes a housing 12 positioned below the panel 11 and a switch control lever 13 is mounted onto a control shaft 14 that extends through a provided opening in the switch housing and in the top panel 11. The switch lever 13 can be rotationally moved as shown as dotted position in FIG. 1 either to the right or to the left, and when it is centered as shown in solid lines, it is in an off position.

The housing 12 includes a center divider member 15 and a top member 16 which is attached just below the panel 11. Shaft 14 is rotatably mounted in suitable bearings -17 and 18, which are mounted between the center divider 15 and the top member or wall 16. The shaft 14 in turn mounts a spur gear 20. The gear has a hub that rides against a flange on the bearing 17, and the bearing 18 is shouldered so that the top wall 16 holds the assembly in position. Note that the bearing 18 has a small neck that surrounds the shaft at the opening in the top wall.

The first or drive gear 20 engages a driven gear 21 that is substantially smaller than the gear 20 and which is, as shown, drivably mounted onto a shaft of a rotary, center tap potentiometer 22. The potentiometer is fastened with suitable fastening means 23 to the divider member or wall 15 and is positioned below the divider wall. The shaft of the potentiometer extends upwardly above the divider wall. The gears are meshed so that the potentiometer 22, which is a center tap, center off, rotary potentiometer, is off when the switch lever 13 is in its 011? position.

The positioning of the switch lever is controlled through the use of a pair of control rods 24 and 25. The control rods each pass through a guide block 26 that is positioned above the divider wall 15 and below the top wall 16 and is held in place with suitable fasteners. The openings in the guide blocks 26 are made so that they form recessed spring pockets 27 surrounding each of the control rods 24 and 25. The control rods pass through small openings at one end of the spring pockets 27. A separate spring 30 surrounds each of the control rods and is positioned within the respective pockets, and a spring retainer washer 31 is positioned adjacent the ends of the control rods and is held in place by brazing or otherwise fastening a suitable fastener 32 to the end of the rod.

The rods are urged by the springs 30 in the direction indicated by arrow 33 and in the first form of the invention are stopped from movement in this direction by stop blocks 34 and 35, respectively, which in turn are fastened onto a center member 36 of the guide member. The stop members or blocks 34 and 35 can be adjustably mounted on the center member 36 so that they can be moved to position the stops where desired.

The rods 24 and 25, respectively, each have bent over end portions 24A and 25A, respectively, and these end portions extend substantially at right angles to the main part of the rods. The end portions are positioned within a part annular slot 37 defined through gear 20. The slot 37 extends part way around the periphery of the gear. The slot is made so that the end surfaces 38 of the slot 37- is engaged by the rod end portions 24A and 25A at the same time that the fasteners 32 engage the respective stop blocks 34 and 35.

Now, it can be seen, that the springs 30 exert a linear force on the rods and the rods in turn pull against the end surfaces 38 of the slot 37. This prevents rotation of the gear except when the spring force of one of the springs 30 is overcome. The centering of the switch in its desired position is thus very accurately done. Upon rotation of the switch lever 13, it can be seen that a gear 20 will be rotated. Assuming that the gear is rotated clockwise as viewed in FIG. 4, the rod 24 will be pulled along with the gear and the spring 30 surrounding the rod 24 will be compressed. The rod 25 will be held against its stop and the end 25A will merely ride in the slot 37 as the gear rotates. When the switch is released, the spring 30 surrounding the rod 24 will urge the rod in direction as indicated by arrow 33 thus pulling the gear 20 in a counterclockwise direction until it is centered again in its home position. Turning the lever 13 in the counterclockwise direction results in the movement of the rod 25 and compression of the spring 30 surrounding this rod, while the rod 24 stays in its home position. When the lever 13 is released, the spring 30 surrounding rod 25 will again urge the rod in the direction as indicated by arrow 33 and move the gear 20 in a counterclockwise direction to its home position.

The rotation of the gear 20 will cause the gear 21 to rotate and thus will rotate the center tap potentiometer. The gear ratio gives substantially full travel of the potentiometer with a small movement of the control lever.

FIG. shows a schematic representation using the switch of the present invention in a typical circuit to control a servo valve coil. The servo valve can be used to control the flow of oil to a rotary hydraulic motor which in turn can be used to drive rotational components, for example, a grip of a remote manipulator. Servo valve controls are made so that the more current flowing through the servo valve coil, the more the valve will open and the faster the motor will rotate.

Upon rotation of the switch lever 13 the wiper 40 of the center tap potentiometer 22 will be moved. In the center position, it can be seen that the wiper goes to ground and is off. For operation in this circuit, two voltage sources, one having a minus 12 volts and one having a plus 12 volts is used.

When the wiper 40 is moved in either direction on the potentiometer by movement of the lever 13, current will flow through the wiper from either the plus 12 or the minus 12 volt source and through a combination of two diodes 44 and 45 and transistors 42 and 43 to supply power to a coil 41 of a servo valve. The amount of power flowing, depends on the position of the wiper 40 and the farther the lever 13 is rotated, the less resistance from the potentiometer 22 there is in the circuit, and the more current that will be flowing through the coil 41.

The more current to coil 41, the more the valve opens and the faster the speed of operation of the motor. When the wiper 40 is moved in the opposite direction from its center position, current will flow in the opposite direction through the circuit causing a reverse current flow in the coil 41 (on the minus 12. volts source the positive is grounded) thereby causing the valve controlled by the coil 41 to open in the opposite direction and cause opposite rotation of its controlled motor. Thus, if the unit is used, for example, for a rotating motor for a grip on a remote control manipulator you can obtain opposite rotation of this grip merely by moving the lever 13 in the opposite direction from its center off position. With electric motors the switch can take the place of the linear switches shown in US. Pat. No. 3,247,979.

Referring to FIG. 6 and a modified form of the invention, it can be seen that the stop blocks 34 and 35 in this form of the invention have been replaced with micro switches 50 and 51. These switches are fastened to the center member 36 in any desired manner in a position so that their actuator buttons align with the rods 24 and 25, respectively. The small collars surrounding the actuator buttons of the switches 50 and 51 form sto members when the actuator buttons are depressed by the rods. The switches 50 and 51 are adjusted so that the actuators are depressed (or actuated) on both of the switches when the lever 13 is in its normal or off position. The switches can be wired into a circuit to obtain reversing functions in combination with a servo valve when only single polarity straight DC power is provided, for example, where the unit uses a 12 volt storage battery.

This circuit is shown schematically in FIG. 7. Lever 13 again drives the gears to move the center wiper 40 on the rotary, center tap potentiometer 22. The center position is again oif and leads to ground as shown. Only a plus 12 volt source is used. The solid line portions of micro switches 50 and 51 is when the lever 13 is in its ofif position. When lever 13 is rotated so that the rod 24 moves away from the switch 50, the switch will move to its dotted position as shown in FIG. 7 and at the same time the wiper 40 will move away from the center position so that current will flow from the voltage source through the wiper, and through a transistor 54 provided in circuit. The micro switch 50 moves to its dotted position and this completes a path through the transistor and the potentiometer to the solenoid servo valve coil 52. Again, the amount of current flowing through the coil 52 determines the amount of opening of the valve that the coil controls in the conventional manner and this in turn, if the valve is used to control a hydraulic motor, will determine the speed of the hydraulic motor. Thus, the farther the lever 13 is rotated from its center position, the faster the motor controlled ,by the coil 52 will rotate.

If the switch lever 13 is moved in its opposite direction, the wiper 40 moves in opposite direction along the resistance of potentiometer 22, and micro switch 51 moves to its dotted position, while the micro switch 50 remains in its solid position. This then completes a circuit for current flow in opposite direction through the servo valve coil 52 to cause the valve to open in opposite direction and cause rotation of its control motor in opposite direction. Again, if the wiper 40 is moved farther in this direction, the current flowing through the servo valve coil will increase and the valve will open more causing the hydraulic motor it controls to rotate faster, thus providing for a speed control proportional to the amount of rotation of lever 13. Not only that, the micro switches of this circuit provide for reversing where a unidirectional current only is utilized.

All of the components necessary for operation of the switch, other than the external power connections can be mounted within the housing 12. Referring again to FIG. 2, it can be seen that the transistors 42 and 43 can be mounted onto a bracket 46 that is fastened to the divider member 15, and the diodes 44 and 45 also can be mounted right within the housing. Suitable resistors that are necessary are easily housed within this switch component as well.

When the form of the invention shown in FIGS. 6 and 7 is utilized, all the components necessary for the circuit except the external power connection also are housed within the switch housing. The transistor 54 can be mounted in place of the transistor 42 and any resistors necessary also fit nicely within this housing.

A junction block 55 can be provided at the bottom of the housing in both forms of the invention so that external connections can also be easily made.

Thus, the use of the linearly slidable rods or links using compression springs for positive centering make the operation of the rotary switch accurate. By proper selection of the gear ratio, the amount of rotation of the lever 13 can be kept to a minimum for obtaining full travel of the potentiometer, and the sensitivity thus can also be controlled by gear ratio selection. As shown, the gears are approximately 15 tooth gear for the gear 21, and a 50 tooth gear for gear 20.

The use of a single rod and spring for biasing the unit to its center position is also contemplated. The unit can operate in only one direction from the center position as well. The unit will work for other types of transmitted power, as well, but finds special use in the electrical field for controlling rotary otentiometers.

One of the features with the present design is that the springs can be preloaded to exert a positive retaining or positioning force in the switch center position.

What is claimed is:

1. A rotary switch having a center oflf position and movable in opposite directions rotationally from its center off position to complete electrical connections, comprising a housing, a first shaft rotatably mounted in the housing, a first gear drivably mounted on said first shaft, a rotary variable rate controller being mounted on said housing and having a controller shaft, a second gear mounted on the shaft of said rotary controller and engaging said first gear, the first gear having slot means defined therein, said slot means having end surfaces, at least two separate control links, means mounting said control links in said slot means, portions of said control links further being slidably mounted with respect to said housing, bias means urging said control links in first directions, said control links engaging opposite end surfaces of said slot means under the urging of said bias means to center said first gear and first shaft in a normal arcuate position comprising the off position of said rotary switch, rotation of said first shaft from its normal position causing unequal force on the control links from said bias means thereby causing one of said links to exert a centering force on said first gear and first shaft through its respective end surface of said slot means to return said first shaft to its normal position.

2. The combination as specified in claim 1 wherein said variable rate controller is a rotary, center tap potentiometer.

3. The combination as specified in claim 1 and stop means on the housing positioned to prevent movement of said control links in the direction of urging of the bias means past a position wherein the switch is in its center off position.

4. The combination as specified in claim 1 wherein said bias means comprises linearly actuated springs.

5. A rotary switch having a center off position and being movable in opposite directions rotationally from its center off position to complete electrical connections, comprising a housing, a first shaft rotatably mounted in said housing, a first gear drivably mounted on said shaft, a rotary center tap potentiometer mounted on said housing and having a second shaft, a second gear mounted on the second shaft and engaging said first gear, said first gear having slot means defined therein, said slot means having end surfaces, at least two separate control links mounted in said slot means, said control links further be ing slidably mounted with respect to said housing, bias means urging said control links in a first direction, said control links having end portions engaging the end surfaces of said slot means under the urging of said bias means to center said first gear in a normal arcuate position comprising the off position of said rotary switch, separate switch means mounted on said housing, each of said separate switch means being positioned to be actuated by a separate one of said control links, said separate switch means being actuated by its respective control link when the rotary switch is in its center off position, rotation of said first shaft from its center position causing movement of one of said control links away from its associated separate switch means and causing unequal force on said control links from said bias means thereby giving a centering force on said gear and first shaft through said control rods tending to return said first shaft to its normal position.

6. A rotary control device having an off position and being movable rotationally from its off position to control a connected load, comprising a housing, a member rotatably mounted in said housing and movable rotationally to and from a normal position, means connected to said member to control said load responsive to rotational movement thereof, a control rod linearly slidably mounted in said housing, first connecting means between said member and rod to cause linear movement of a portion of said control rod upon rotational movement of said member from the normal position of said member in a first rotational direction, switch means on said housing in alignment with said control rod and being actuated by said control rod when said member is in its normal position, and bias means cooperating with said control rod resisting movement of said member in the first rotational direction from its normal position, rotational movement of said member increasing the biasing force on said control rod tending to move said member back to its normal position.

7. The combination as specified in claim 6 wherein said member is rotatable in first and second rotational directions from its normal position, a second control rod linearly slidably mounted in the housing, second connecting means between said second control rod and said member to cause linear movement of a portion of said second control rod when the member is rotated in the second rotational direction from its normal position, a second switch on said housing in alignment with said second control rod and being actuated by said second control rod with said member in its normal position, bias means on said second control rod resisting movement of the member in the second rotational direction, said first and second connecting means including means to permit relative movement between the member and the first control rod when the member is rotated in said second rotational direction, and to permit relative movement between said member and said second control rod when the member is rotated in said first rotational direction.

8. The combination as specified in claim 7 wherein said control rods are stopped from movement beyond a predetermined position in the direction of urging of their respective bias means.

9. The combination as specified in claim 7 wherein said member includes a disc like member, and said connecting means comprises slot means in said disc like member, said rods having means slidably connecting them in said slot means.

10. The combination as specified in claim 9 wherein said disc like member is a gear.

11. The combination as specified in claim 10 wherein said control means includes a second gear meshing with said first gear, said second gear driving a control member, said control member having means thereon which will vary the controlled function in proportion to the amount of rotation of said second gear from a normal position.

12. The combination as specified in claim 7 wherein said bias means on said control rods comprise linearly actuated springs connected between said housing and said control rod.

13. The combination as specified in claim 12 wherein the control member comprises a center tap rotary potentiometer.

14. The combination as specified in claim 7 wherein the switch means have portions which act as stop means for said rods to prevent movement of said rods under urging of the bias means past a predetermined position.

References Cited UNITED STATES PATENTS FOREIGN PATENTS 992,651 10/1951 France.

ROBERT K. SCHAEFER, Primary Examiner 5 R. A. VANDERHYE, Assistant Examiner Roberton.

Schleicher 74-470 X Newcomb.

Miller.

Kahn et a1. 74470 10 Miller.

US. Cl. X.R.

2 3 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,539,748 Dated November 10, 1970 Invencoz-(s) Karl E. Neumeier It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Claim 13, Line 1 change Claim l2 to --Claim 11-- (Application, Claim 14) SIGNED mu SEALED MR2 I97! B Ana:

Idwm! M. Fletcher, In". 

